From: Char <peacech@gmail.com>
Date: Sun, 15 Feb 2026 16:27:52 +0000 (+0000)
Subject: patch 9.2.0008: MS-Windows: font size calculation may be wrong
X-Git-Tag: v9.2.0008^0
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=13223921e0e80e5ecd472e4db4cba60301b03530;p=thirdparty%2Fvim.git

patch 9.2.0008: MS-Windows: font size calculation may be wrong

Problem:  MS-Windows: font size calculation may be wrong when font does
          not specify a valid ascent value. (Char, after v9.1.2129)
Solution: Calculate ascent as a ratio of ascent to total font height
          with a fallback if metrics are zero.

Fallback to default value when font does not specify ascent value.

As proposed in https://github.com/vim/vim/pull/19318#issuecomment-3864669253

related: #19318
closes:  #19367

Signed-off-by: Char <peacech@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
---

diff --git a/src/gui_dwrite.cpp b/src/gui_dwrite.cpp
index 39a39938b8..c71358717a 100644
--- a/src/gui_dwrite.cpp
+++ b/src/gui_dwrite.cpp
@@ -865,8 +865,14 @@ DWriteContext::CreateTextFormatFromLOGFONT(const LOGFONTW &logFont,
     {
 	*ppTextFormat = pTextFormat;
 	if (pFontAscent != NULL && fontMetrics.designUnitsPerEm != 0)
-	    *pFontAscent = fontSize * float(fontMetrics.ascent)
-		/ float(fontMetrics.designUnitsPerEm);
+	{
+	    // Calculate ascent ratio (0.0 to 1.0) relative to total font height
+	    FLOAT totalHeight = float(fontMetrics.ascent + fontMetrics.descent);
+	    if (totalHeight != 0.0f)
+		*pFontAscent = float(fontMetrics.ascent) / totalHeight;
+	    else
+		*pFontAscent = 0.83f; // fallback
+	}
     }
     else
 	SafeRelease(&pTextFormat);
@@ -1086,7 +1092,7 @@ DWriteContext::DrawText(const WCHAR *text, int len,
 	// font fallback, the metrics change).
 	// Use the pre-calculated font ascent for all text to prevent
 	// vertical shifts during redraw.
-	FLOAT baselineY = FLOAT(y) + mFontAscent;
+	FLOAT baselineY = roundf(FLOAT(y) + FLOAT(h) * mFontAscent + 0.5);
 
 	TextRenderer renderer(this);
 	TextRendererContext context = { color, FLOAT(cellWidth), lpDx, len,
diff --git a/src/version.c b/src/version.c
index 0b693e562c..7615dbdb34 100644
--- a/src/version.c
+++ b/src/version.c
@@ -734,6 +734,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    8,
 /**/
     7,
 /**/